1. Field of the Invention
The invention relates to a new process for the preparation of carboxamides of nitrogen-containing aromatic heterocyclic compounds (N-heterocyclic compounds) and to the use of the carboxamides obtained for the preparation of the corresponding carboxylic acids by alkaline hydrolysis.
2. Background Art
Both the carboxamides and the carboxylic acids of N-heterocyclic compounds are important intermediate products for the preparation of pharmaceuticals. A carbamoylation method for N-heterocyclic compounds is known from German Patent No. 2,056,433. This process is distinguished by the fact that a redox system of R-OOH+iron(II) is used for formation of the carbamoyl radical. R here denotes hydrogen, alkyl or cycloalkyl. Iron(II) must be used here in stochiometric amounts or even in excess, which obviously results in major waste water and waste product problems in the case of syntheses on an industrial scale. The alkyl hydroperoxides used are expensive, and furthermore are hazardous to handle because of their explosiveness.